Magnetic resonance imaging (MRI) apparatuses are utilized for medical applications, industrial applications, and various other fields.
Magnetic resonance imaging apparatuses excite the spin of an object to be inspected placed in a static magnetic field by the nuclear magnetic resonance (NMR) phenomenon and generate a sectional image based on magnetic resonance (MR) signals generated accompanied with the excitation.
In recent years, in magnetic resonance imaging apparatuses, sophisticated imaging methods have been developed along with the advances made in the hardware. Magnetic resonance imaging apparatuses have now been remarkably improved in the technology for the formation of gradient magnetic fields, so shortening of the time of repetition (TR) has become possible. As an imaging method utilizing this, the coherent SSFP (steady state free precession) method is known. The coherent SSFP method is utilized as the imaging methods called the True FISP, Balanced SSFP, FIESTA, etc. In general, in magnetic resonance imaging, shortening of the TR results in the relaxation of the longitudinal magnetization becoming insufficient and lowers the signal intensity, but the coherent SSFP method does not use a spoiler gradient magnetic field, so holds the magnitude of the magnetic moment and makes the phases of transverse magnetization uniform at an intermediate point of time of the RF pulses continuing in the formed steady state, therefore makes an increase of signal intensity of the MR signal etc. possible (see for example Patent Document 1 and Patent Document 2).                Patent Document 1: Japanese Patent No. 2898329        Patent Document 2: Japanese Patent Publication (A) No. 2001-29327        